Selectively injectable chemical additive

Abstract

An apparatus for producing fluid from a wellbore includes production tubing in the wellbore, an annulus around the tubing, and a chemical injection system for injecting chemical additive into the production tubing from the annulus. The chemical additive system includes an injection module with a valve that is selectively opened and closed by operating an actuator. When the valve is opened, the chemical additive is injected into the tubing in response to a pressure differential between the annulus and tubing. The injection module is surface-controlled and downhole conditions are monitored, so that a flow of chemical additive injection is initiated, adjusted, or suspended in real time.

What is claimed is: 
     
       1. A method for producing fluid from a wellbore comprising:
 flowing a produced fluid upwards within production tubing that is disposed in the wellbore; 
 disposing an amount of chemical additive into an annulus that surrounds the production tubing; 
 collecting the chemical additive in the annulus; 
 selectively injecting lift gas into the production tubing at a depth below an upper level of the chemical additive collected in the annulus; and 
 changing a flow regime of the produced fluid by selectively injecting the chemical additive from the annulus and into the production tubing at a depth below an upper level of the chemical additive collected in the annulus. 
 
     
     
       2. The method of  claim 1 , wherein the step of injecting is through a chemical injection module that is mounted onto the production tubing. 
     
     
       3. The method of  claim 2 , further comprising selectively controlling a flowrate of chemical additive being injected into the production tubing by injecting the chemical additive through a particular quantity of chemical injection modules. 
     
     
       4. The method of  claim 3 , wherein a controller in communication with sensors in the wellbore is configured to selectively control a flowrate of chemical additive being injected into the production tubing. 
     
     
       5. The method of  claim 1 , wherein the chemical additive is disposed into the annulus through a chemical additive supply line having a discharge end deep in the annulus and proximate where the chemical additive is being injected into the production tubing. 
     
     
       6. The method of  claim 1 , wherein the flow regime is a slug flow, and the chemical additive comprises a foaming agent that alters the slug flow inside the production tubing into a steady flow regime. 
     
     
       7. The method of  claim 6 , wherein the slug flow is identified based on conditions inside the production tubing that are sensed by sensors. 
     
     
       8. The method of  claim 1 , wherein the chemical additive further removes scale or corrosion inside the production tubing. 
     
     
       9. The method of  claim 1 , wherein the chemical additive mitigates an anomaly inside the production tubing that is selected from the group consisting of scale in the tubing, corrosion in the tubing, foam in the tubing, and combinations thereof. 
     
     
       10. The method of  claim 1 , wherein the chemical additive is introduced into the annulus through an opening on a lower end of a capillary that is disposed in the well, and wherein the opening is selectively blocked by a check valve attached to a lowermost end of the capillary and disposed adjacent a packer at a bottom of the annulus. 
     
     
       11. The method of  claim 1 , further comprising injecting lift gas into the production tubing through a lift gas injection module mounted to the production tubing. 
     
     
       12. The method of  claim 11 , wherein the lift gas is routed to the lift gas injection module through a snorkel having an end in communication with lift gas in the annulus. 
     
     
       13. The method of  claim 1 , wherein an amount of chemical injection is controlled by adjusting an orifice size. 
     
     
       14. A method for producing fluid from a wellbore comprising:
 flowing a produced fluid upwards within production tubing that is disposed in the wellbore; 
 disposing an amount of chemical additive into an annulus that surrounds the production tubing; 
 collecting the chemical additive in the annulus; 
 monitoring pressure and temperature in the wellbore in real time: 
 comparing the real time pressure and temperature to pressure and temperature at which an anomaly is expected to occur; 
 identifying that the anomaly is likely to occur based on the step of comparing; and 
 injecting the chemical additive from the annulus and into the production tubing based on the step of identifying. 
 
     
     
       15. The method of  claim 14 , further comprising monitoring fluid flow rate or flow regime in real time and comparing the real time fluid flow rate or flow regime to fluid flow rate or flow regime at which an anomaly is expected to occur. 
     
     
       16. The method of  claim 14 , wherein the anomaly comprises precipitation in the production tubing. 
     
     
       17. The method of  claim 14 , wherein the real time pressure and temperature is monitored in the annulus, or within tubing, or both. 
     
     
       18. The method of  claim 14 , wherein the chemical additive is being injected in real time into the production tubing through a surface controlled chemical injection module in the annulus that is submerged in the chemical additive. 
     
     
       19. The method of  claim 18 , further comprising controlling a flowrate of the chemical additive being injected in real time by adjusting an orifice size in a valve in the chemical injection module or by injecting the chemical additive through a particular quantity of chemical injection modules.